A CAP (carrierless amplitude and phase) modulator is described in U.S. Pat. No. 4,924,492 to Gitlin et al.
Use of adaptive notch filters having constrained poles and zeros to eliminate narrow-band or sine wave components with unknown frequencies from observed time series is described in Stoica, P. and Nehorai, A., "Performance analysis of an adaptive notch filter with constrained poles and zeros", IEEE Transactions on Acoustics, Speech and Signal Processing, 36(6), June 1988, and in Ng, T. S., "Some aspects of an adaptive digital notch filter with constrained poles and zeros", IEEE Transactions on Acoustics, Speech and Signal Processing, ASSP-35(2), February 1987.
The disclosures of all publications mentioned in the specification and of the publications cited therein are hereby incorporated by reference.